An optical connection between optic fibers can be effected by fusion or mechanical splicing. In general, fusion splicing involves joining two optic fibers end-to-end and effecting optical connection using heat and mechanical splicing involves holding two optic fibers in alignment so that light can pass from one to another.
The equipment used to effect fusion splicing is cumbersome and relatively expensive. Further the equipment may not be readily portable.
For mechanical splicing, fibers cores are either passively or actively aligned. Passive alignment relies on precision reference surfaces, generally grooves or cylindrical holes, to align fiber cores during splicing. Active alignment involves the use of light for accurate fiber alignment, and may consist of either monitoring the loss through the splice during splice alignment or by using a microscope to accurately align the fiber cores for splicing. To monitor loss, either an optical source and optical power meter or an optical time domain reflectometer (OTDR) are used.
In many circumstances, the above-described splicing methods either produce inaccurate results or take too long to precisely align optic fibers. Also, human error is prevalent in splicing operations performed in the field (i.e. splices made in cables mounted to telegraph poles) due to movement of the operator, time pressures, or simply due to the degree of accuracy required to ensure a precise splice.
In addition to the above mentioned difficulties with mechanical and fusion splicing, the ends of the optic fibers typically need to be cleaved before splicing is effected. A cleave is a deliberate, controlled break, intended to create a perfectly flat end face, perpendicular to the longitudinal axis of the fiber. A cleave is typically made by first introducing a microscopic fracture (“nick”) into the fiber with a special tool which has a sharp blade of some hard material, such as diamond, sapphire, or tungsten carbide. If proper tension is applied to the fiber as the nick is made, or immediately afterward, then the fracture will propagate in a controlled fashion, creating the desired end face. The cleaving process involves the use of specialised equipment that is relatively expensive and may not be readily portable for a technician to take from job to job.
It is generally desirable to overcome or ameliorate one or more of the above mentioned difficulties, or at least provide a useful alternative.